Re: [Help-smalltalk] [rfc] regex rewrite

[Mike Anderson]

Paolo Bonzini wrote:
> > I also think it would be more useful if =~ returned MatchResult/nil 
> > instead of true/false.
>
> There's #searchRegex: for that.  The "=~" name seemed more like a 
> boolean query to me.

There's #matchRegex: '.*whatever.*' for that :)

I just don't think that what it does is sufficiently useful to devote 
the =~ operator to it.

Both Perl and Ruby return values that can be interpreted as true/false 
from =~, but both of them also capture the matched expression and 
sub-expressions into variables. We don't have that possibility, so I 
think =~ should work harder.

> Here is a new version of the patch (only the regex.st parts) that 
> supports cute things like
>
> st> ^'abc' copyFrom: 1 to: 3 replacingRegex: 'a(.)c' with: 'X%1Z'!
> 'XbZ'

That is nice. I did wonder whether backslashes would be better, but 
eventually decided that I could live with percents.

BTW there is a missing period in #copyFrom:to:replacingAllRegex:with:.

Mike

--- smalltalk-2.1g-regex/examples/regex.st      2005-05-30 17:05:02.399926760 
+0000
+++ smalltalk-2.1g-mod/examples/regex.st        2005-05-30 23:33:38.161392248 
+0000
@@ -436,19 +436,21 @@
     regex := pattern asRegex.
     res := WriteStream on: (String new: to - from + 1).
     idx := from.
-    [
-        regs := self searchRegex: regex from: idx to: to.
-        beg >= 1
-       regs notNil
-    ] whileTrue: [
-       beg := regs from.
-       end := regs to.
-       res next: beg - idx putAll: self startingAt: idx.
-       res nextPutAll: (str bindWithArguments: regs).
-       idx := end + 1.
-       beg > end ifTrue: [ res nextPut: (self at: idx). idx := idx + 1 ].
-       idx > self size ifTrue: [ ^res contents ].
-    ].
+    [  regs := self searchRegex: regex from: idx to: to.
+        beg >= 1.
+               regs notNil     ] 
+               whileTrue: 
+               [ beg := regs from.
+               end := regs to.
+               res next: beg - idx putAll: self startingAt: idx.
+               res nextPutAll: (str bindWithArguments: regs).
+               idx := end + 1.
+               beg > end 
+                       ifTrue: 
+                               [ res nextPut: (self at: idx). 
+                               idx := idx + 1 ].
+               idx > self size 
+                       ifTrue: [ ^res contents ]. ].
     res next: to - idx + 1 putAll: self startingAt: idx.
 
     ^res contents